Optimization of the ultrasound protocol to increase the proliferation and viability of periodontium cells

Abstract

Orthodontic tooth movement relies on coordinated tissue resorption and formation in the surrounding bone and periodontal ligament. The resorptionformation sequence remodeling process of the bone and periodontal ligament is performed and controlled by the cellular activity. Understanding biology has had a great impact on clinical orthodontics, essentially how we can accelerate orthodontic movement and thus reduce treatment times. Surgical and nonsurgical interventions are being tested to move teeth faster. Low-intensity pulsed ultrasound (LIPUS) is a non-invasive technique that accelerates tooth movement however there are few studies of its clinical application. This study, in addition to summarizing the effect of in vitro mechanical stimuli on the cells involved in orthodontic movement, also highlights the best ultrasound conditions to which the osteoblasts and fibroblasts must be submitted. Design: human fetal osteoblast cell line (HFOB) and a human primary cell line (hPDLF) were cultured in vitro and subjected in a first phase to different ultrasound parameters (1 MHz and 1.5 MHz; 30mW/cm2 and 60mW/cm2 during 5 and 10 min). After observing the 3 timepoints (1h, 24h and 72h) the best conditions were daily stimulated up to 3 days. Results: In our study, for both types of cells, the 1 MHz, 30 mW/cm2 for 5 min was the condition that provided the best metabolic activity. Further cellular studies should be conducted to understand the effect of using ultrasound as promising therapy in accelerating orthodontic movement.